In the next project period, we propose to examine further the determinants of the latency of the off-response. It has been found, in preliminary experiments, that the latency varies with the length of the stimulus train and with the potassium concentration of the extracellular space. It seems also to vary with the mass of the muscle strip examined. These variables will be examined further. Also, we will continue to look into the nature of the aerobic metabolism that is required for maintenance of the tone of the lower esophageal sphincter.